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1 /*
2  * Intel Multimedia Timer device implementation for SGI SN platforms.
3  *
4  * This file is subject to the terms and conditions of the GNU General Public
5  * License.  See the file "COPYING" in the main directory of this archive
6  * for more details.
7  *
8  * Copyright (c) 2001-2004 Silicon Graphics, Inc.  All rights reserved.
9  *
10  * This driver exports an API that should be supportable by any HPET or IA-PC
11  * multimedia timer.  The code below is currently specific to the SGI Altix
12  * SHub RTC, however.
13  *
14  * 11/01/01 - jbarnes - initial revision
15  * 9/10/04 - Christoph Lameter - remove interrupt support for kernel inclusion
16  * 10/1/04 - Christoph Lameter - provide posix clock CLOCK_SGI_CYCLE
17  * 10/13/04 - Christoph Lameter, Dimitri Sivanich - provide timer interrupt
18  *              support via the posix timer interface
19  */
20
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/ioctl.h>
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/errno.h>
27 #include <linux/mm.h>
28 #include <linux/devfs_fs_kernel.h>
29 #include <linux/mmtimer.h>
30 #include <linux/miscdevice.h>
31 #include <linux/posix-timers.h>
32 #include <linux/interrupt.h>
33
34 #include <asm/uaccess.h>
35 #include <asm/sn/addrs.h>
36 #include <asm/sn/intr.h>
37 #include <asm/sn/shub_mmr.h>
38 #include <asm/sn/nodepda.h>
39 #include <asm/sn/shubio.h>
40
41 MODULE_AUTHOR("Jesse Barnes <jbarnes@sgi.com>");
42 MODULE_DESCRIPTION("SGI Altix RTC Timer");
43 MODULE_LICENSE("GPL");
44
45 /* name of the device, usually in /dev */
46 #define MMTIMER_NAME "mmtimer"
47 #define MMTIMER_DESC "SGI Altix RTC Timer"
48 #define MMTIMER_VERSION "2.0"
49
50 #define RTC_BITS 55 /* 55 bits for this implementation */
51
52 extern unsigned long sn_rtc_cycles_per_second;
53
54 #define RTC_COUNTER_ADDR        ((long *)LOCAL_MMR_ADDR(SH_RTC))
55
56 #define rtc_time()              (*RTC_COUNTER_ADDR)
57
58 static int mmtimer_ioctl(struct inode *inode, struct file *file,
59                          unsigned int cmd, unsigned long arg);
60 static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
61
62 /*
63  * Period in femtoseconds (10^-15 s)
64  */
65 static unsigned long mmtimer_femtoperiod = 0;
66
67 static struct file_operations mmtimer_fops = {
68         .owner =        THIS_MODULE,
69         .mmap =         mmtimer_mmap,
70         .ioctl =        mmtimer_ioctl,
71 };
72
73 /*
74  * We only have comparison registers RTC1-4 currently available per
75  * node.  RTC0 is used by SAL.
76  */
77 #define NUM_COMPARATORS 3
78 /* Check for an RTC interrupt pending */
79 static int inline mmtimer_int_pending(int comparator)
80 {
81         if (HUB_L((unsigned long *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED)) &
82                         SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator)
83                 return 1;
84         else
85                 return 0;
86 }
87 /* Clear the RTC interrupt pending bit */
88 static void inline mmtimer_clr_int_pending(int comparator)
89 {
90         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED_ALIAS),
91                 SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator);
92 }
93
94 /* Setup timer on comparator RTC1 */
95 static void inline mmtimer_setup_int_0(u64 expires)
96 {
97         u64 val;
98
99         /* Disable interrupt */
100         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 0UL);
101
102         /* Initialize comparator value */
103         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), -1L);
104
105         /* Clear pending bit */
106         mmtimer_clr_int_pending(0);
107
108         val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC1_INT_CONFIG_IDX_SHFT) |
109                 ((u64)cpu_physical_id(smp_processor_id()) <<
110                         SH_RTC1_INT_CONFIG_PID_SHFT);
111
112         /* Set configuration */
113         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_CONFIG), val);
114
115         /* Enable RTC interrupts */
116         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 1UL);
117
118         /* Initialize comparator value */
119         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), expires);
120
121
122 }
123
124 /* Setup timer on comparator RTC2 */
125 static void inline mmtimer_setup_int_1(u64 expires)
126 {
127         u64 val;
128
129         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 0UL);
130
131         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), -1L);
132
133         mmtimer_clr_int_pending(1);
134
135         val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC2_INT_CONFIG_IDX_SHFT) |
136                 ((u64)cpu_physical_id(smp_processor_id()) <<
137                         SH_RTC2_INT_CONFIG_PID_SHFT);
138
139         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_CONFIG), val);
140
141         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 1UL);
142
143         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), expires);
144 }
145
146 /* Setup timer on comparator RTC3 */
147 static void inline mmtimer_setup_int_2(u64 expires)
148 {
149         u64 val;
150
151         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 0UL);
152
153         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), -1L);
154
155         mmtimer_clr_int_pending(2);
156
157         val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC3_INT_CONFIG_IDX_SHFT) |
158                 ((u64)cpu_physical_id(smp_processor_id()) <<
159                         SH_RTC3_INT_CONFIG_PID_SHFT);
160
161         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_CONFIG), val);
162
163         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 1UL);
164
165         HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), expires);
166 }
167
168 /*
169  * This function must be called with interrupts disabled and preemption off
170  * in order to insure that the setup succeeds in a deterministic time frame.
171  * It will check if the interrupt setup succeeded.
172  */
173 static int inline mmtimer_setup(int comparator, unsigned long expires)
174 {
175
176         switch (comparator) {
177         case 0:
178                 mmtimer_setup_int_0(expires);
179                 break;
180         case 1:
181                 mmtimer_setup_int_1(expires);
182                 break;
183         case 2:
184                 mmtimer_setup_int_2(expires);
185                 break;
186         }
187         /* We might've missed our expiration time */
188         if (rtc_time() < expires)
189                 return 1;
190
191         /*
192          * If an interrupt is already pending then its okay
193          * if not then we failed
194          */
195         return mmtimer_int_pending(comparator);
196 }
197
198 static int inline mmtimer_disable_int(long nasid, int comparator)
199 {
200         switch (comparator) {
201         case 0:
202                 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE),
203                         0UL) : REMOTE_HUB_S(nasid, SH_RTC1_INT_ENABLE, 0UL);
204                 break;
205         case 1:
206                 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE),
207                         0UL) : REMOTE_HUB_S(nasid, SH_RTC2_INT_ENABLE, 0UL);
208                 break;
209         case 2:
210                 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE),
211                         0UL) : REMOTE_HUB_S(nasid, SH_RTC3_INT_ENABLE, 0UL);
212                 break;
213         default:
214                 return -EFAULT;
215         }
216         return 0;
217 }
218
219 #define TIMER_OFF 0xbadcabLL
220
221 /* There is one of these for each comparator */
222 typedef struct mmtimer {
223         spinlock_t lock ____cacheline_aligned;
224         struct k_itimer *timer;
225         int i;
226         int cpu;
227         struct tasklet_struct tasklet;
228 } mmtimer_t;
229
230 /*
231  * Total number of comparators is comparators/node * MAX nodes/running kernel
232  */
233 static mmtimer_t timers[NUM_COMPARATORS*MAX_COMPACT_NODES];
234
235 /**
236  * mmtimer_ioctl - ioctl interface for /dev/mmtimer
237  * @inode: inode of the device
238  * @file: file structure for the device
239  * @cmd: command to execute
240  * @arg: optional argument to command
241  *
242  * Executes the command specified by @cmd.  Returns 0 for success, < 0 for
243  * failure.
244  *
245  * Valid commands:
246  *
247  * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
248  * of the page where the registers are mapped) for the counter in question.
249  *
250  * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
251  * seconds
252  *
253  * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
254  * specified by @arg
255  *
256  * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
257  *
258  * %MMTIMER_MMAPAVAIL - Returns 1 if the registers can be mmap'd into userspace
259  *
260  * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
261  * in the address specified by @arg.
262  */
263 static int mmtimer_ioctl(struct inode *inode, struct file *file,
264                          unsigned int cmd, unsigned long arg)
265 {
266         int ret = 0;
267
268         switch (cmd) {
269         case MMTIMER_GETOFFSET: /* offset of the counter */
270                 /*
271                  * SN RTC registers are on their own 64k page
272                  */
273                 if(PAGE_SIZE <= (1 << 16))
274                         ret = (((long)RTC_COUNTER_ADDR) & (PAGE_SIZE-1)) / 8;
275                 else
276                         ret = -ENOSYS;
277                 break;
278
279         case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
280                 if(copy_to_user((unsigned long __user *)arg,
281                                 &mmtimer_femtoperiod, sizeof(unsigned long)))
282                         return -EFAULT;
283                 break;
284
285         case MMTIMER_GETFREQ: /* frequency in Hz */
286                 if(copy_to_user((unsigned long __user *)arg,
287                                 &sn_rtc_cycles_per_second,
288                                 sizeof(unsigned long)))
289                         return -EFAULT;
290                 ret = 0;
291                 break;
292
293         case MMTIMER_GETBITS: /* number of bits in the clock */
294                 ret = RTC_BITS;
295                 break;
296
297         case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
298                 ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
299                 break;
300
301         case MMTIMER_GETCOUNTER:
302                 if(copy_to_user((unsigned long __user *)arg,
303                                 RTC_COUNTER_ADDR, sizeof(unsigned long)))
304                         return -EFAULT;
305                 break;
306         default:
307                 ret = -ENOSYS;
308                 break;
309         }
310
311         return ret;
312 }
313
314 /**
315  * mmtimer_mmap - maps the clock's registers into userspace
316  * @file: file structure for the device
317  * @vma: VMA to map the registers into
318  *
319  * Calls remap_pfn_range() to map the clock's registers into
320  * the calling process' address space.
321  */
322 static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
323 {
324         unsigned long mmtimer_addr;
325
326         if (vma->vm_end - vma->vm_start != PAGE_SIZE)
327                 return -EINVAL;
328
329         if (vma->vm_flags & VM_WRITE)
330                 return -EPERM;
331
332         if (PAGE_SIZE > (1 << 16))
333                 return -ENOSYS;
334
335         vma->vm_flags |= (VM_IO | VM_SHM | VM_LOCKED );
336         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
337
338         mmtimer_addr = __pa(RTC_COUNTER_ADDR);
339         mmtimer_addr &= ~(PAGE_SIZE - 1);
340         mmtimer_addr &= 0xfffffffffffffffUL;
341
342         if (remap_pfn_range(vma, vma->vm_start, mmtimer_addr >> PAGE_SHIFT,
343                                         PAGE_SIZE, vma->vm_page_prot)) {
344                 printk(KERN_ERR "remap_pfn_range failed in mmtimer.c\n");
345                 return -EAGAIN;
346         }
347
348         return 0;
349 }
350
351 static struct miscdevice mmtimer_miscdev = {
352         SGI_MMTIMER,
353         MMTIMER_NAME,
354         &mmtimer_fops
355 };
356
357 static struct timespec sgi_clock_offset;
358 static int sgi_clock_period;
359
360 /*
361  * Posix Timer Interface
362  */
363
364 static struct timespec sgi_clock_offset;
365 static int sgi_clock_period;
366
367 static int sgi_clock_get(clockid_t clockid, struct timespec *tp)
368 {
369         u64 nsec;
370
371         nsec = rtc_time() * sgi_clock_period
372                         + sgi_clock_offset.tv_nsec;
373         tp->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tp->tv_nsec)
374                         + sgi_clock_offset.tv_sec;
375         return 0;
376 };
377
378 static int sgi_clock_set(clockid_t clockid, struct timespec *tp)
379 {
380
381         u64 nsec;
382         u64 rem;
383
384         nsec = rtc_time() * sgi_clock_period;
385
386         sgi_clock_offset.tv_sec = tp->tv_sec - div_long_long_rem(nsec, NSEC_PER_SEC, &rem);
387
388         if (rem <= tp->tv_nsec)
389                 sgi_clock_offset.tv_nsec = tp->tv_sec - rem;
390         else {
391                 sgi_clock_offset.tv_nsec = tp->tv_sec + NSEC_PER_SEC - rem;
392                 sgi_clock_offset.tv_sec--;
393         }
394         return 0;
395 }
396
397 /*
398  * Schedule the next periodic interrupt. This function will attempt
399  * to schedule a periodic interrupt later if necessary. If the scheduling
400  * of an interrupt fails then the time to skip is lengthened
401  * exponentially in order to ensure that the next interrupt
402  * can be properly scheduled..
403  */
404 static int inline reschedule_periodic_timer(mmtimer_t *x)
405 {
406         int n;
407         struct k_itimer *t = x->timer;
408
409         t->it.mmtimer.clock = x->i;
410         t->it_overrun--;
411
412         n = 0;
413         do {
414
415                 t->it.mmtimer.expires += t->it.mmtimer.incr << n;
416                 t->it_overrun += 1 << n;
417                 n++;
418                 if (n > 20)
419                         return 1;
420
421         } while (!mmtimer_setup(x->i, t->it.mmtimer.expires));
422
423         return 0;
424 }
425
426 /**
427  * mmtimer_interrupt - timer interrupt handler
428  * @irq: irq received
429  * @dev_id: device the irq came from
430  * @regs: register state upon receipt of the interrupt
431  *
432  * Called when one of the comarators matches the counter, This
433  * routine will send signals to processes that have requested
434  * them.
435  *
436  * This interrupt is run in an interrupt context
437  * by the SHUB. It is therefore safe to locally access SHub
438  * registers.
439  */
440 static irqreturn_t
441 mmtimer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
442 {
443         int i;
444         mmtimer_t *base = timers + cpuid_to_cnodeid(smp_processor_id()) *
445                                                 NUM_COMPARATORS;
446         unsigned long expires = 0;
447         int result = IRQ_NONE;
448
449         /*
450          * Do this once for each comparison register
451          */
452         for (i = 0; i < NUM_COMPARATORS; i++) {
453                 /* Make sure this doesn't get reused before tasklet_sched */
454                 spin_lock(&base[i].lock);
455                 if (base[i].cpu == smp_processor_id()) {
456                         if (base[i].timer)
457                                 expires = base[i].timer->it.mmtimer.expires;
458                         /* expires test won't work with shared irqs */
459                         if ((mmtimer_int_pending(i) > 0) ||
460                                 (expires && (expires < rtc_time()))) {
461                                 mmtimer_clr_int_pending(i);
462                                 tasklet_schedule(&base[i].tasklet);
463                                 result = IRQ_HANDLED;
464                         }
465                 }
466                 spin_unlock(&base[i].lock);
467                 expires = 0;
468         }
469         return result;
470 }
471
472 void mmtimer_tasklet(unsigned long data) {
473         mmtimer_t *x = (mmtimer_t *)data;
474         struct k_itimer *t = x->timer;
475         unsigned long flags;
476
477         if (t == NULL)
478                 return;
479
480         /* Send signal and deal with periodic signals */
481         spin_lock_irqsave(&t->it_lock, flags);
482         spin_lock(&x->lock);
483         /* If timer was deleted between interrupt and here, leave */
484         if (t != x->timer)
485                 goto out;
486         t->it_overrun = 0;
487
488         if (tasklist_lock.write_lock || posix_timer_event(t, 0) != 0) {
489
490                 // printk(KERN_WARNING "mmtimer: cannot deliver signal.\n");
491
492                 t->it_overrun++;
493         }
494         if(t->it.mmtimer.incr) {
495                 /* Periodic timer */
496                 if (reschedule_periodic_timer(x)) {
497                         printk(KERN_WARNING "mmtimer: unable to reschedule\n");
498                         x->timer = NULL;
499                 }
500         } else {
501                 /* Ensure we don't false trigger in mmtimer_interrupt */
502                 t->it.mmtimer.expires = 0;
503         }
504         t->it_overrun_last = t->it_overrun;
505 out:
506         spin_unlock(&x->lock);
507         spin_unlock_irqrestore(&t->it_lock, flags);
508 }
509
510 static int sgi_timer_create(struct k_itimer *timer)
511 {
512         /* Insure that a newly created timer is off */
513         timer->it.mmtimer.clock = TIMER_OFF;
514         return 0;
515 }
516
517 /* This does not really delete a timer. It just insures
518  * that the timer is not active
519  *
520  * Assumption: it_lock is already held with irq's disabled
521  */
522 static int sgi_timer_del(struct k_itimer *timr)
523 {
524         int i = timr->it.mmtimer.clock;
525         cnodeid_t nodeid = timr->it.mmtimer.node;
526         mmtimer_t *t = timers + nodeid * NUM_COMPARATORS +i;
527         unsigned long irqflags;
528
529         if (i != TIMER_OFF) {
530                 spin_lock_irqsave(&t->lock, irqflags);
531                 mmtimer_disable_int(cnodeid_to_nasid(nodeid),i);
532                 t->timer = NULL;
533                 timr->it.mmtimer.clock = TIMER_OFF;
534                 timr->it.mmtimer.expires = 0;
535                 spin_unlock_irqrestore(&t->lock, irqflags);
536         }
537         return 0;
538 }
539
540 #define timespec_to_ns(x) ((x).tv_nsec + (x).tv_sec * NSEC_PER_SEC)
541 #define ns_to_timespec(ts, nsec) (ts).tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &(ts).tv_nsec)
542
543 /* Assumption: it_lock is already held with irq's disabled */
544 static void sgi_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
545 {
546
547         if (timr->it.mmtimer.clock == TIMER_OFF) {
548                 cur_setting->it_interval.tv_nsec = 0;
549                 cur_setting->it_interval.tv_sec = 0;
550                 cur_setting->it_value.tv_nsec = 0;
551                 cur_setting->it_value.tv_sec =0;
552                 return;
553         }
554
555         ns_to_timespec(cur_setting->it_interval, timr->it.mmtimer.incr * sgi_clock_period);
556         ns_to_timespec(cur_setting->it_value, (timr->it.mmtimer.expires - rtc_time())* sgi_clock_period);
557         return;
558 }
559
560
561 static int sgi_timer_set(struct k_itimer *timr, int flags,
562         struct itimerspec * new_setting,
563         struct itimerspec * old_setting)
564 {
565
566         int i;
567         unsigned long when, period, irqflags;
568         int err = 0;
569         cnodeid_t nodeid;
570         mmtimer_t *base;
571
572         if (old_setting)
573                 sgi_timer_get(timr, old_setting);
574
575         sgi_timer_del(timr);
576         when = timespec_to_ns(new_setting->it_value);
577         period = timespec_to_ns(new_setting->it_interval);
578
579         if (when == 0)
580                 /* Clear timer */
581                 return 0;
582
583         if (flags & TIMER_ABSTIME) {
584                 struct timespec n;
585                 unsigned long now;
586
587                 getnstimeofday(&n);
588                 now = timespec_to_ns(n);
589                 if (when > now)
590                         when -= now;
591                 else
592                         /* Fire the timer immediately */
593                         when = 0;
594         }
595
596         /*
597          * Convert to sgi clock period. Need to keep rtc_time() as near as possible
598          * to getnstimeofday() in order to be as faithful as possible to the time
599          * specified.
600          */
601         when = (when + sgi_clock_period - 1) / sgi_clock_period + rtc_time();
602         period = (period + sgi_clock_period - 1)  / sgi_clock_period;
603
604         /*
605          * We are allocating a local SHub comparator. If we would be moved to another
606          * cpu then another SHub may be local to us. Prohibit that by switching off
607          * preemption.
608          */
609         preempt_disable();
610
611         nodeid =  cpuid_to_cnodeid(smp_processor_id());
612         base = timers + nodeid * NUM_COMPARATORS;
613 retry:
614         /* Don't use an allocated timer, or a deleted one that's pending */
615         for(i = 0; i< NUM_COMPARATORS; i++) {
616                 if (!base[i].timer && !base[i].tasklet.state) {
617                         break;
618                 }
619         }
620
621         if (i == NUM_COMPARATORS) {
622                 preempt_enable();
623                 return -EBUSY;
624         }
625
626         spin_lock_irqsave(&base[i].lock, irqflags);
627
628         if (base[i].timer || base[i].tasklet.state != 0) {
629                 spin_unlock_irqrestore(&base[i].lock, irqflags);
630                 goto retry;
631         }
632         base[i].timer = timr;
633         base[i].cpu = smp_processor_id();
634
635         timr->it.mmtimer.clock = i;
636         timr->it.mmtimer.node = nodeid;
637         timr->it.mmtimer.incr = period;
638         timr->it.mmtimer.expires = when;
639
640         if (period == 0) {
641                 if (!mmtimer_setup(i, when)) {
642                         mmtimer_disable_int(-1, i);
643                         posix_timer_event(timr, 0);
644                         timr->it.mmtimer.expires = 0;
645                 }
646         } else {
647                 timr->it.mmtimer.expires -= period;
648                 if (reschedule_periodic_timer(base+i))
649                         err = -EINVAL;
650         }
651
652         spin_unlock_irqrestore(&base[i].lock, irqflags);
653
654         preempt_enable();
655
656         return err;
657 }
658
659 static struct k_clock sgi_clock = {
660         .res = 0,
661         .clock_set = sgi_clock_set,
662         .clock_get = sgi_clock_get,
663         .timer_create = sgi_timer_create,
664         .nsleep = do_posix_clock_nonanosleep,
665         .timer_set = sgi_timer_set,
666         .timer_del = sgi_timer_del,
667         .timer_get = sgi_timer_get
668 };
669
670 /**
671  * mmtimer_init - device initialization routine
672  *
673  * Does initial setup for the mmtimer device.
674  */
675 static int __init mmtimer_init(void)
676 {
677         unsigned i;
678
679         if (!ia64_platform_is("sn2"))
680                 return -1;
681
682         /*
683          * Sanity check the cycles/sec variable
684          */
685         if (sn_rtc_cycles_per_second < 100000) {
686                 printk(KERN_ERR "%s: unable to determine clock frequency\n",
687                        MMTIMER_NAME);
688                 return -1;
689         }
690
691         mmtimer_femtoperiod = ((unsigned long)1E15 + sn_rtc_cycles_per_second /
692                                2) / sn_rtc_cycles_per_second;
693
694         for (i=0; i< NUM_COMPARATORS*MAX_COMPACT_NODES; i++) {
695                 spin_lock_init(&timers[i].lock);
696                 timers[i].timer = NULL;
697                 timers[i].cpu = 0;
698                 timers[i].i = i % NUM_COMPARATORS;
699                 tasklet_init(&timers[i].tasklet, mmtimer_tasklet, (unsigned long) (timers+i));
700         }
701
702         if (request_irq(SGI_MMTIMER_VECTOR, mmtimer_interrupt, SA_PERCPU_IRQ, MMTIMER_NAME, NULL)) {
703                 printk(KERN_WARNING "%s: unable to allocate interrupt.",
704                         MMTIMER_NAME);
705                 return -1;
706         }
707
708         strcpy(mmtimer_miscdev.devfs_name, MMTIMER_NAME);
709         if (misc_register(&mmtimer_miscdev)) {
710                 printk(KERN_ERR "%s: failed to register device\n",
711                        MMTIMER_NAME);
712                 return -1;
713         }
714
715         sgi_clock_period = sgi_clock.res = NSEC_PER_SEC / sn_rtc_cycles_per_second;
716         register_posix_clock(CLOCK_SGI_CYCLE, &sgi_clock);
717
718         printk(KERN_INFO "%s: v%s, %ld MHz\n", MMTIMER_DESC, MMTIMER_VERSION,
719                sn_rtc_cycles_per_second/(unsigned long)1E6);
720
721         return 0;
722 }
723
724 module_init(mmtimer_init);
725